org.camunda.bpm.engine.authorization.Permission Maven / Gradle / Ivy
/*
* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
* under one or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. Camunda licenses this file to you under the Apache License,
* Version 2.0; you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.camunda.bpm.engine.authorization;
/**
* A permission represents an authorization to interact with a given
* resource in a specific way. See {@link Permissions} for a set of built-in
* permissions and {@link Authorization} for general overview on authorizations.
*
* In Camunda Platform, multiple permissions are grouped into an {@link Authorization}.
* For efficient storage and checking of authorizations, the permissons that make
* up an authorization are coded into a single integer.
* The implication of this design is that a permission must have a unique integer value
* and it must be a power of two, ie 2^0, 2^1, 2^2, 2^3, 2^4 ...
*
* The permission can then be added to an authorization using bitwise OR:
*
* Auth: 0000001001001
* Perm to add: 0000000010000
* bit OR (|) : 0000001011001
*
*
* and removed using bitwise AND of the inverted value:
*
* Auth: 0000001001001
* Perm to rem: 0000000001000
* invert (~) : 1111111110111
* bit AND (&): 0000001000001
*
*
* Defining a custom Permission
* The XxxPermissions classes contains the values of the built-in
* permissions (i.e. {@link Permissions}, {@link ProcessDefinitionPermissions},
* {@link ProcessInstancePermissions}, {@link TaskPermissions},
* all can be found in {@link org.camunda.bpm.engine.authorization authorization} package).
* In order to define a custom permission, you must provide
* an implementation of this interface such that the {@link #getValue()}
* method returns an integer which is a power of two and not yet used by any of the
* built-in Permissions. Keep the Permission's names unique as well.
* You must implement also {@link #getTypes()} and make sure that
* the permission values are not already reserved for the desired
* {@link Resource}.
*
*
* @author Daniel Meyer
* @since 7.0
*/
public interface Permission {
/** returns the name of the permission, ie. 'UPDATE' */
String getName();
/** returns the unique numeric value of the permission.
* Must be a power of 2. ie 2^0, 2^1, 2^2, 2^3, 2^4 ... */
int getValue();
/** returns the resource types which are allowed for this permission */
Resource[] getTypes();
}